A Lagrangian numerical method, known as Smoothed Particle Hydrodynamics (SPH), has been applied to simulate debris flows triggering and resulting propagation over a hillside located in the city of Nocera Inferiore (Southern Italy). Debris flows have been simulated since long time for hazard mitigation assessment or deposit evaluation; despite so, only recently they have been reproduced by means of Lagrangian approaches, like for example the FEM method. Such a numerical technique shows as main drawback the development of a distorted mesh. Heavy grid refinement algorithms are therefore necessary, where large deformations are present. SPH overcomes such difficulties since no mesh is laid over the physical domain. Spatial discretization is indeed carried out with a collection of so called “particles” without connectivity law am ong them. While boundary particles are fixed over time, computing particles are free to move in response to external and internal forces such as gravity and pressu re. In more detail, computing particles are all initially “frozen”. Once a particle is “unfrozen” it starts moving and it triggers a change in pressure in the neighbouring particles: when a pressure threshold plim is reached, other particles are set in motion and the movement evolves. Runout velocity is controlled by handling the shear stress taubed with the fixed bed. Varying the location of the triggering point, the pressure threshold plim and the shear stress taubed allow to perform a sensitivity analysis on the flooded area. A preliminary test comparison is made with corresponding Flow-3D results.
Modelling Triggering And Evolution Of Debris Flows With Smoothed Particle Hydrodynamics
VICCIONE, GIACOMO;BOVOLIN, Vittorio
2010
Abstract
A Lagrangian numerical method, known as Smoothed Particle Hydrodynamics (SPH), has been applied to simulate debris flows triggering and resulting propagation over a hillside located in the city of Nocera Inferiore (Southern Italy). Debris flows have been simulated since long time for hazard mitigation assessment or deposit evaluation; despite so, only recently they have been reproduced by means of Lagrangian approaches, like for example the FEM method. Such a numerical technique shows as main drawback the development of a distorted mesh. Heavy grid refinement algorithms are therefore necessary, where large deformations are present. SPH overcomes such difficulties since no mesh is laid over the physical domain. Spatial discretization is indeed carried out with a collection of so called “particles” without connectivity law am ong them. While boundary particles are fixed over time, computing particles are free to move in response to external and internal forces such as gravity and pressu re. In more detail, computing particles are all initially “frozen”. Once a particle is “unfrozen” it starts moving and it triggers a change in pressure in the neighbouring particles: when a pressure threshold plim is reached, other particles are set in motion and the movement evolves. Runout velocity is controlled by handling the shear stress taubed with the fixed bed. Varying the location of the triggering point, the pressure threshold plim and the shear stress taubed allow to perform a sensitivity analysis on the flooded area. A preliminary test comparison is made with corresponding Flow-3D results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
